Dual Plate System Research Articles

Effect of Plate Configuration in the Primary Stability of Osteotomies and Biological Reconstructions of Femoral Defects: Finite-Element Study.

Osteosynthesis is an alternative treatment for stabilizing femur-bone traumas. The initial stability of the fixation systems is one of the biomechanical parameters affecting implant failure and bone union, especially in surgeries of intercalary reconstructions after the removal of bone tumors. This study aimed to investigate the initial biomechanical effect of using one or two osteosynthesis plate configurations for femoral fixation and the effect of fastening the allograft to the osteosynthesis plate in the case of femoral allograft reconstructions. Three finite-element models of a femur with three different fixation conditions for a transverse osteotomy in the middle of the diaphysis, i.e., using one and two osteosynthesis plates and an intercalary allograft, were constructed. An eight-hole compression plate and a six-hole second plate were used to simulate osteosynthesis plates. The plate screws were tightened previously to the loading, and the tightening sequences simulate the bolt-tightening procedure in a surgical environment. The models were imported into the ADINA System for nonlinear analysis, using compression loads applied over the femur head. Models with the dual fixation systems had the most outstanding compression stiffness. The femur head movement in the dual plate system was 24.8% smaller than in the single plate system. A statistical analysis of a region of interest (VOI) placed in the femur diaphysis showed that the biomechanical effect of using the dual plate system is smaller in the osteotomy region than at the femur head, e.g., a displacement average decrease of only 5% between the two systems, while the maximum value decreases by 26.8%. The allograft fixation to the second osteosynthesis plate leads to an improvement in the system stability. The results presented in this work show that including the bolt analysis in the femoral diaphysis osteotomy fixation will allow for capturing the nonlinear behavior of the osteotomy region more realistically. The stability of the intercalary reconstruction of the femoral diaphysis was higher when the allograft was fastened to the second osteosynthesis plate.

Increased hyphal branching and growth of ectomycorrhizal fungus Lactarius rufus by the helper bacterium Paenibacillus sp

Paenibacillus sp. EJP73 has been previously demonstrated as a mycorrhization helper bacterium (MHB) for the Lactarius rufus-Pinus sylvestris symbiosis in both laboratory and glasshouse experiments. In the present study, the effect of Paenibacillus sp. EJP73 metabolites on L. rufus EO3 pre-symbiotic growth was tested in two agar plate-based systems. Specifically, volatile metabolites were investigated using a dual plate system, in which the presence of strain EJP73 resulted in a significant negative effect on L. rufus EO3 hyphal radial growth but enhanced hyphal branching and reduced internode distance. Soluble metabolites produced by strain EJP73 were tested on L. rufus EO3 growth in single-agar plate assays by incorporating bacterial cell-free whole or molecular weight fraction spent broth into the agar. Whole spent broth had a negative effect on hyphal growth, whereas a low molecular weight fraction (100-1,000) promoted colony radial growth. Headspace and spent broth analysis of strain EJP73 cultures revealed 2,5-diisopropylpyrazine to be the most significant component. Synthesised 2,5-diisopropylpyrazine and elevated CO2 (2,000 ppm) were tested as specific volatile metabolites in the dual plate system, but neither produced the response shown when strain EJP73 was present. Increased pre-symbiotic hyphal branching leading to increased likelihood of plant infection may be an important MHB mechanism for strain EJP73. Although the precise signal molecules could not be identified, the work suggests a number of metabolites may work synergistically to increase L. rufus root colonisation.